The present invention relates to a seal for the side arm of a stopcock of the kind used in apparatus for monitoring pressure in the human blood vessel and, more particularly, to a seal that will permit blood samples to be taken or the line to be flushed through the side arm but which minimizes the access of bacteria to the blood vessel system through the side arm.
In certain medical procedures it is necessary and desirable to monitor the pressure existing in a blood vessel. Part of the system that has been used in the past for accomplishing this blood vessel pressure monitoring is shown schematically in FIG. 1 wherein a first tube 1 is connected to a catheter (not shown) inserted in a patient's blood vessel, and a second tube 2 is connected to monitoring equipment (also not shown). A T-shaped stopcock 10 is connected into the pressure-monitoring line to provide a means for drawing blood, introducing medicament or for otherwise permitting access to the system. Stopcock 10 has a first connection 12 connected to tube 1 and a second connection 14 connected to tube 2 and a side arm 16 with lumen 18 through which access may be gained to the pressure line. Stopcock valve 20 is supported for rotation in an annular housing 22 and may be selectively rotated by means of lever 24 to provide fluid communication between tubes 1 and 2 or between tube 1 and side arm 16. The end of side arm 16 may be fitted with a Luer lock fitting 17 which may include an annular flange extending radially outwardly from the end of side arm 16 or may include one or more tabs (not shown) extending radially outwardly to provide a means onto which female Luer lock fitting 19 may be threaded.
In the past, when it has been desired to take a blood sample the nose 26 of, for example, a blood collection syringe 28 is inserted into lumen 18 of side arm 16 or in the alternative, may be Luer locked onto flange 17 of side arm 16 using Luer lock fitting 19. Stopcock lever 24 is then positioned to permit fluid communication between tube 1 and side arm 16 and to block tube 2. Blood is then drawn and stopcock lever 24 is returned to its original position permitting fluid flow between tubes 1 and 2 and blocking side arm 16. Syringe 28 is then removed.
In the past, side arm lumen 18 and the inside of valve 22 have been open to the atmosphere. After a blood sample has been collected, a certain amount of residual blood may remain coated on the inside surfaces of side arm lumen 18 and on stopcock valve 22. This has provided a site for bacteria growth. The next time blood is drawn from the apparatus and valve 22 is rotated, some of this bacteria may be rotated into fluid communication with tubes 1 and 2 in the main pressure monitoring line and into the main fluid path. This can contaminate the fluid path and can deliver bacteria through the pressure monitoring system to the patient. Since the side arm lumen is often used for the injection of medicament into the patient, any bacteria existing in the lumen or on the valve can be injected directly into the patient along with the medicament. Complications due to secondary infections may result from bacteria ingress through the stopcock mechanism.
The present invention addresses this problem of bacteria ingress through the stopcock mechanism by providing a seal 30 for the stopcock side arm.